Effect of coccidial challenge and vaccination on the performance, veterinary postmortem scores, and blood biochemistry of broiler chickens.

A total of 960 male Cobb 500 broilers were used in a growth performance study to explore the effect of coccidial vaccination and/or coccidial challenge on blood biochemistry and veterinary postmortem metrics. Day-old chicks were randomly divided into one of the 4 experimental treatments. Treatments were arranged in a 2 × 2 factorial arrangement, with the factors being without or with vaccination (administered on day 1) or coccidial challenge (oral gavage on day 7). Growth performance was monitored on a weekly basis. Blood sample collection, as well as full veterinary necropsies, were carried out on days 6, 8, 13, 20, 27, and 34. Birds that did not receive the vaccination but were challenged with coccidiosis had higher feed conversion ratio, lower body weights, and higher mortality than the other experimental groups, and this effect was particularly evident from day 13 to day 20. Birds challenged with coccidiosis had lower plasma sodium and total carotenoid concentrations and higher potassium and globulin concentrations than nonchallenged birds. Significant interactions between age and experimental treatment for these blood parameters were observed, particularly on day 13. The necropsy results confirmed the effectiveness of the challenge and vaccination treatments, wherein birds that were challenged had higher coccidiosis scores on day 13 and day 27 than birds that were not challenged. These results demonstrate the potential for plasma sodium, potassium, total protein, total carbon dioxide, globulin, and carotenoid analysis for early diagnosis of coccidiosis in growing broiler chickens. Further work is necessary to establish whether the changes in blood biochemistry observed in the present study are transferable to alternative flocks of chicken and whether early diagnosis and intervention may mitigate performance losses associated with this disease.

Effect of broiler genetics, age, and gender on performance and blood chemistry.

A total of 640 broilers were used to determine the effects of strain, sex, and age on hematology and blood chemistry using rapid detection devices. Day old chicks from two genetic lines of common fast-growing and high-yield broiler strains were sexed and allocated to 40 pens (16 birds per pen) containing either male or female and Ross or Cobb strains (n = 10). Venous blood was analyzed weekly using 2 broilers from each pen (n = 20) using the i-STAT® Alinity Handheld Clinical Analyzer, Zoetis Vetscan VS2, and iCheck™ Carotene devices at 14, 21, 28, 35, and 42 d, as well as growth performance. Post-mortem health tracking metrics were also recorded on 42 d. Broilers were deemed healthy based on posting data results and performed in accordance with industry standards with males presenting greater BW and reduced FCR than female broilers. Ross broilers displayed greater BW to 14 d with similar FCR compared with Cobb birds. Day of age had a highly significant impact on blood calcium, phosphorus, potassium, sodium, chloride, carotene, aspartate aminotransferase, creatine kinase, bile acids, uric acid, total protein, albumin, globulin, total carbon dioxide, hematocrit, and malondialdehyde. Male broilers had reduced blood sodium, chloride, carotene, uric acid, albumin, and increased total protein, glucose, and total carbon dioxide. Ross broilers had greater blood potassium, and sodium, as well as reduced uric acid, total protein, globulin, and malondialdehyde, compared with Cobb birds. These results demonstrated the effectiveness of point-of-care devices in measuring blood chemistry and hematology in modern broilers. These data can be utilized to determine normal healthy blood ranges in these types of broilers when accounting for strain, sex, and age.

Dietary potassium and available phosphorous on broiler growth performance, carcass characteristics, and wooden breast.

Broiler dietary potassium (K) and available phosphorous (AvP) have decreased in recent years but both ions are intimately involved in the elimination of hydrogen ions that are produced during rapid growth. It was hypothesized that the decrease of these dietary electrolytes was related to the development of myopathies, and thus increased dietary K and/or AvP would reduce the occurrence of breast myopathies. A total of 320 Ross male broiler chicks were placed into 16 pens and fed 2 diet series containing either decreasing AvP levels of 0.45, 0.40, and 0.35% in the starter, grower, and finisher diets, respectively (Decline), or a fixed AvP of 0.45% in all dietary phases (Fixed). To complete a 2 × 2 design either normal basal dietary K (K-) (0.86, 0.77, 0.68%) or added dietary K (K+) (1.01, 0.93, 0.88%) were also applied to starter, grower, and finisher diets, respectively. Blood physiology was measured at 29 and 42 d. Carcass data, wooden breast and white striping scores were measured at 35 and 43 d. The K+ diets improved feed conversion ratio at 35 d (1.52 vs 1.57 g: g), reduced body weight at 42 d (3524 vs 3584 g), reduced hemoglobin (6.83 vs 7.58 g/dL), and packed cell volume (20.1 vs 22.3%) at 29 d, reduced ionized blood calcium (1.42 vs 1.47 mmol/L) at 42 d, and reduced partial pressure of blood CO2 (49.1 vs 54.7 mm/Hg) at 42 d relative to broilers fed basal K- diets (P < 0.05). Fixed AvP diets improved feed conversion ratio at 28 and 42 d, increased percentage breast meat (28.85 vs 27.58%) and carcass water pickup (2.72 vs 1.42%) at 35 d, and reduced wooden breast (2.88 vs 3.69) at 43 d (P < 0.05).

Dietary amino acids under hypoxic conditions exacerbates muscle myopathies including wooden breast and white stripping.

The occurrence of wooden breast (WB) and white striping (WS) of broiler breast myopathies may be associated with least-cost feed formulations and the inclusion of greater amounts of synthetic amino acids. Two experiments were conducted to evaluate the effects of supplemental glutamine (Gln-/+, 0 and 1%) and arginine (Arg-/+, 0 and 0.25%) in a 2 × 2 factorial arrangement. Experiment 1 consisted of 8 replicates using 32 pens and focused on live performance to 44 d of age, carcass yield, and meat quality evaluations at 45 d of age. Live performance parameters including feed intake, BW gain, mortality, and feed conversion were evaluated. Post-harvest carcass yield, breast muscle quality (including WB and WS), proximate analysis, and mineral analysis of breast muscle and tibia bone were also evaluated. Experiment 2 comprised 4 replicates using 8 pens with weekly measurements of blood physiology and muscle myopathy development from 21 to 45 d of age. Broilers fed supplemental Gln and Arg (Gln+/Arg+) produced broilers with greater BW and improved FCR. The WB and WS severity increased with Gln+ diets, while only WB increased using Arg+ diets. Weekly observations revealed the greatest increase in WB myopathies occurred between 28 to 35 d, while WS significantly increased one week later (35 to 42 d). When comparing broilers of similar BW at 45 d, Gln+ diets resulted in greater WS scores and percentage breast muscle fat. Further analysis of WB and WS scores (independent of treatment affect) revealed that increased myopathy scores were associated with increased blood CO2, H2CO3, and reduced O2 with increased meat pH, moisture content, and Ca concentration. These results indicated that increased muscle Ca is associated with increased WB, while increased dietary glutamine and lack of oxygen may have resulted in a reverse flux of the citric acid cycle and reduced electron transport chain activity resulting in increased WS.